* [linux-next:master 1570/2472] mm/kasan/init.c:318:9: warning: variable 'pud' set but not used
@ 2020-11-01 23:31 kernel test robot
2020-11-03 0:17 ` Linus Walleij
0 siblings, 1 reply; 4+ messages in thread
From: kernel test robot @ 2020-11-01 23:31 UTC (permalink / raw)
To: Linus Walleij
Cc: kbuild-all, Linux Memory Management List, Russell King,
Ard Biesheuvel, Abbott Liu, Florian Fainelli
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tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head: 4e78c578cb987725eef1cec7d11b6437109e9a49
commit: 421015713b306e47af95d4d61cdfbd96d462e4cb [1570/2472] ARM: 9017/2: Enable KASan for ARM
config: arm-randconfig-r025-20201030 (attached as .config)
compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=421015713b306e47af95d4d61cdfbd96d462e4cb
git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
git fetch --no-tags linux-next master
git checkout 421015713b306e47af95d4d61cdfbd96d462e4cb
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
mm/kasan/init.c: In function 'kasan_free_pud':
>> mm/kasan/init.c:318:9: warning: variable 'pud' set but not used [-Wunused-but-set-variable]
318 | pud_t *pud;
| ^~~
--
In file included from include/trace/define_trace.h:103,
from include/trace/events/rcu.h:785,
from kernel/rcu/rcu.h:13,
from kernel/rcu/update.c:49:
include/trace/events/rcu.h: In function 'perf_trace_rcu_torture_read':
>> include/trace/events/rcu.h:724:3: warning: 'strncpy' specified bound 8 equals destination size [-Wstringop-truncation]
724 | strncpy(__entry->rcutorturename, rcutorturename,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
725 | RCUTORTURENAME_LEN);
| ~~~~~~~~~~~~~~~~~~~
include/trace/perf.h:66:4: note: in definition of macro 'DECLARE_EVENT_CLASS'
66 | { assign; } \
| ^~~~~~
include/trace/trace_events.h:79:9: note: in expansion of macro 'PARAMS'
79 | PARAMS(assign), \
| ^~~~~~
include/trace/events/rcu.h:11:25: note: in expansion of macro 'TRACE_EVENT'
11 | #define TRACE_EVENT_RCU TRACE_EVENT
| ^~~~~~~~~~~
include/trace/events/rcu.h:723:2: note: in expansion of macro 'TP_fast_assign'
723 | TP_fast_assign(
| ^~~~~~~~~~~~~~
In file included from include/trace/define_trace.h:102,
from include/trace/events/rcu.h:785,
from kernel/rcu/rcu.h:13,
from kernel/rcu/update.c:49:
include/trace/events/rcu.h: In function 'trace_event_raw_event_rcu_torture_read':
>> include/trace/events/rcu.h:724:3: warning: 'strncpy' specified bound 8 equals destination size [-Wstringop-truncation]
724 | strncpy(__entry->rcutorturename, rcutorturename,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
725 | RCUTORTURENAME_LEN);
| ~~~~~~~~~~~~~~~~~~~
include/trace/trace_events.h:695:4: note: in definition of macro 'DECLARE_EVENT_CLASS'
695 | { assign; } \
| ^~~~~~
include/trace/trace_events.h:79:9: note: in expansion of macro 'PARAMS'
79 | PARAMS(assign), \
| ^~~~~~
include/trace/events/rcu.h:11:25: note: in expansion of macro 'TRACE_EVENT'
11 | #define TRACE_EVENT_RCU TRACE_EVENT
| ^~~~~~~~~~~
include/trace/events/rcu.h:723:2: note: in expansion of macro 'TP_fast_assign'
723 | TP_fast_assign(
| ^~~~~~~~~~~~~~
--
In file included from include/trace/define_trace.h:103,
from include/trace/events/fscache.h:533,
from fs/fscache/internal.h:28,
from fs/fscache/main.c:16:
include/trace/events/fscache.h: In function 'perf_trace_fscache_netfs':
>> include/trace/events/fscache.h:208:7: warning: 'strncpy' specified bound 8 equals destination size [-Wstringop-truncation]
208 | strncpy(__entry->name, netfs->name, 8);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/trace/perf.h:66:4: note: in definition of macro 'DECLARE_EVENT_CLASS'
66 | { assign; } \
| ^~~~~~
include/trace/trace_events.h:79:9: note: in expansion of macro 'PARAMS'
79 | PARAMS(assign), \
| ^~~~~~
include/trace/events/fscache.h:196:1: note: in expansion of macro 'TRACE_EVENT'
196 | TRACE_EVENT(fscache_netfs,
| ^~~~~~~~~~~
include/trace/events/fscache.h:206:6: note: in expansion of macro 'TP_fast_assign'
206 | TP_fast_assign(
| ^~~~~~~~~~~~~~
In file included from include/trace/define_trace.h:102,
from include/trace/events/fscache.h:533,
from fs/fscache/internal.h:28,
from fs/fscache/main.c:16:
include/trace/events/fscache.h: In function 'trace_event_raw_event_fscache_netfs':
>> include/trace/events/fscache.h:208:7: warning: 'strncpy' specified bound 8 equals destination size [-Wstringop-truncation]
208 | strncpy(__entry->name, netfs->name, 8);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/trace/trace_events.h:695:4: note: in definition of macro 'DECLARE_EVENT_CLASS'
695 | { assign; } \
| ^~~~~~
include/trace/trace_events.h:79:9: note: in expansion of macro 'PARAMS'
79 | PARAMS(assign), \
| ^~~~~~
include/trace/events/fscache.h:196:1: note: in expansion of macro 'TRACE_EVENT'
196 | TRACE_EVENT(fscache_netfs,
| ^~~~~~~~~~~
include/trace/events/fscache.h:206:6: note: in expansion of macro 'TP_fast_assign'
206 | TP_fast_assign(
| ^~~~~~~~~~~~~~
vim +/pud +318 mm/kasan/init.c
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 315
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 316 static void kasan_free_pud(pud_t *pud_start, p4d_t *p4d)
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 317 {
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 @318 pud_t *pud;
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 319 int i;
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 320
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 321 for (i = 0; i < PTRS_PER_PUD; i++) {
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 322 pud = pud_start + i;
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 323 if (!pud_none(*pud))
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 324 return;
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 325 }
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 326
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 327 pud_free(&init_mm, (pud_t *)page_to_virt(p4d_page(*p4d)));
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 328 p4d_clear(p4d);
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 329 }
0207df4fa1a8692 mm/kasan/kasan_init.c Andrey Ryabinin 2018-08-17 330
:::::: The code at line 318 was first introduced by commit
:::::: 0207df4fa1a869281ddbf72db6203dbf036b3e1a kernel/memremap, kasan: make ZONE_DEVICE with work with KASAN
:::::: TO: Andrey Ryabinin <aryabinin@virtuozzo.com>
:::::: CC: Linus Torvalds <torvalds@linux-foundation.org>
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
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^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [linux-next:master 1570/2472] mm/kasan/init.c:318:9: warning: variable 'pud' set but not used
2020-11-01 23:31 [linux-next:master 1570/2472] mm/kasan/init.c:318:9: warning: variable 'pud' set but not used kernel test robot
@ 2020-11-03 0:17 ` Linus Walleij
2020-11-03 8:22 ` Ard Biesheuvel
0 siblings, 1 reply; 4+ messages in thread
From: Linus Walleij @ 2020-11-03 0:17 UTC (permalink / raw)
To: kernel test robot
Cc: kbuild-all, Linux Memory Management List, Russell King,
Ard Biesheuvel, Abbott Liu, Florian Fainelli, Linux ARM
On Mon, Nov 2, 2020 at 12:32 AM kernel test robot <lkp@intel.com> wrote:
> mm/kasan/init.c: In function 'kasan_free_pud':
> >> mm/kasan/init.c:318:9: warning: variable 'pud' set but not used [-Wunused-but-set-variable]
> 318 | pud_t *pud;
> | ^~~
So this is because
arch/arm/include/asm/pgtable-2level.h has:
#define pud_none(pud) (0)
because of the way that PMDs are folded into the PUD.
(See the comment in the file.)
This is not liked by KASan because it looks like the pud
variable is unused.
Any suggestions? Should it be:
#define pud_none(pud) (!pud_val(pud))
Like most other archs?
I also toyed with just putting __maybe_unused into the kasan init.
Any other ways to solve this?
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [linux-next:master 1570/2472] mm/kasan/init.c:318:9: warning: variable 'pud' set but not used
2020-11-03 0:17 ` Linus Walleij
@ 2020-11-03 8:22 ` Ard Biesheuvel
2020-11-06 8:53 ` Linus Walleij
0 siblings, 1 reply; 4+ messages in thread
From: Ard Biesheuvel @ 2020-11-03 8:22 UTC (permalink / raw)
To: Linus Walleij
Cc: kernel test robot, kbuild-all, Linux Memory Management List,
Russell King, Abbott Liu, Florian Fainelli, Linux ARM
On Tue, 3 Nov 2020 at 01:17, Linus Walleij <linus.walleij@linaro.org> wrote:
>
> On Mon, Nov 2, 2020 at 12:32 AM kernel test robot <lkp@intel.com> wrote:
>
> > mm/kasan/init.c: In function 'kasan_free_pud':
> > >> mm/kasan/init.c:318:9: warning: variable 'pud' set but not used [-Wunused-but-set-variable]
> > 318 | pud_t *pud;
> > | ^~~
>
> So this is because
> arch/arm/include/asm/pgtable-2level.h has:
> #define pud_none(pud) (0)
> because of the way that PMDs are folded into the PUD.
> (See the comment in the file.)
>
> This is not liked by KASan because it looks like the pud
> variable is unused.
>
> Any suggestions? Should it be:
> #define pud_none(pud) (!pud_val(pud))
> Like most other archs?
>
> I also toyed with just putting __maybe_unused into the kasan init.
>
> Any other ways to solve this?
>
What about
diff --git a/mm/kasan/init.c b/mm/kasan/init.c
index fe6be0be1f76..7c3eb1f5a439 100644
--- a/mm/kasan/init.c
+++ b/mm/kasan/init.c
@@ -315,12 +315,10 @@ static void kasan_free_pmd(pmd_t *pmd_start, pud_t *pud)
static void kasan_free_pud(pud_t *pud_start, p4d_t *p4d)
{
- pud_t *pud;
int i;
for (i = 0; i < PTRS_PER_PUD; i++) {
- pud = pud_start + i;
- if (!pud_none(*pud))
+ if (!pud_none(pud_start[i]))
return;
}
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [linux-next:master 1570/2472] mm/kasan/init.c:318:9: warning: variable 'pud' set but not used
2020-11-03 8:22 ` Ard Biesheuvel
@ 2020-11-06 8:53 ` Linus Walleij
0 siblings, 0 replies; 4+ messages in thread
From: Linus Walleij @ 2020-11-06 8:53 UTC (permalink / raw)
To: Ard Biesheuvel
Cc: kernel test robot, kbuild-all, Linux Memory Management List,
Russell King, Abbott Liu, Florian Fainelli, Linux ARM
On Tue, Nov 3, 2020 at 9:22 AM Ard Biesheuvel <ardb@kernel.org> wrote:
> What about
>
> diff --git a/mm/kasan/init.c b/mm/kasan/init.c
> index fe6be0be1f76..7c3eb1f5a439 100644
> --- a/mm/kasan/init.c
> +++ b/mm/kasan/init.c
> @@ -315,12 +315,10 @@ static void kasan_free_pmd(pmd_t *pmd_start, pud_t *pud)
>
> static void kasan_free_pud(pud_t *pud_start, p4d_t *p4d)
> {
> - pud_t *pud;
> int i;
>
> for (i = 0; i < PTRS_PER_PUD; i++) {
> - pud = pud_start + i;
> - if (!pud_none(*pud))
> + if (!pud_none(pud_start[i]))
> return;
> }
Yeah that is way better, also makes the code a lot easier to read.
I sent a patch rewriting all the kasan_free_p??() calls like this.
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 4+ messages in thread
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2020-11-01 23:31 [linux-next:master 1570/2472] mm/kasan/init.c:318:9: warning: variable 'pud' set but not used kernel test robot
2020-11-03 0:17 ` Linus Walleij
2020-11-03 8:22 ` Ard Biesheuvel
2020-11-06 8:53 ` Linus Walleij
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